1. Field of the Invention
The present invention is related to very large scale integrated circuit chips and more specifically to apparatus for optimizing the operating parameters of a voltage regulator mounted on the surface of a very large scale integrated circuit chip package.
2. Prior Art
A chip or die is a substrate on which active and passive components of an integrated circuit are fabricated. In order to plug into a socket on a printed circuit board, the chip is mounted in a pin grid array (PGA) ceramic package. In prior very large scale integrated circuit (VSLI) chips the supply voltage at which the components on the chip operate is 5 volts. Newer products designed to operate in low power personal computers operate at 3.3 volts. In order to allow a chip that is designed to 3.3 volt specification to operate in existing systems that operate with 5 volts, voltage regulators with a 5 volt to 3.3 volt conversion capability are mounted on the surface of the PGA package.
The response of a voltage regulator to changes in load is called the transient response, and the magnitude of the voltage deviations at the voltage regulator output is controlled in a particular application by the value of output capacitance selected. The output capacitor supplies current to load during the response and recovery time of the voltage regulator. On-package voltage regulation introduces unique requirements which must be met in the selection of the correct capacitors.
It is desirable to provide optimum values for capacitors to improve the transient response of an on-package voltage regulator.
It is desirable to permit new parts operating at 3.3 volts to operate in printed circuit boards with either 3.3 volt or 5 volt wiring.
It is desirable to provide dual voltage operation of a integrated circuit chip package having an on-package voltage regulator.